Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
  • C09B35/00—Disazo and polyazo dyes of the type A<-D->B prepared by diazotising and coupling
  • C09B35/02—Disazo dyes
  • C09B35/039—Disazo dyes characterised by the tetrazo component
  • C09B35/04—Disazo dyes characterised by the tetrazo component the tetrazo component being a benzene derivative
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
  • C09B41/00—Special methods of performing the coupling reaction
  • C09B41/001—Special methods of performing the coupling reaction characterised by the coupling medium

Definitions

• the present invention relates to a process for the preparation of disazo dyestuffs.
• the present invention provides a novel process for the preparation of disazo dyestuffs of the formula (I) ##STR4## in which R 1 and R 2 represent, independent of each other, a hydrogen atom or a water-insolubilizing substituent, such as a halogen atom, for example a chlorine or bromine atom, or an alkyl or alkoxy group having from 1 to 4 carbon atoms, R 3 and R 4 represent, independent of each other, a hydrogen atom or a water-insolubilizing substituent, for example a halogen atom, such as a chlorine or bromine atom, or a nitro, trifluoromethyl, alkyl or alkoxy group having from 1 to 4 carbon atoms, and wherein the OH groups stand in the 2- or 4-position to the azo groups, which comprises diazotizing a 2- or 4-hydroxy-4'-aminoazobenzene of the formula (II) ##STR5## in which R 1 , R 2 , R 3 and R 4 are
• the novel process of the invention is particularly important in the preparation of the disazo dyestuffs of the formula (I) which are valuable for dyeing and which have as their basis hydroxyazobenzenes of the formula (II), which are present in admixture with phenols of the formula (III). Mixtures of this kind are obtained, if for the preparation of the compounds (II) there are used as starting compounds monodiazotized p-phenylenediamines of the formula (IV) ##STR7## in which R 3 and R 4 are defined as above, since the corresponding 4-amino-benzene-diazonium salts can only be coupled advantageously in a considerable excess of phenols of the formula (III).
• the diazotization of the hydroxyaminoazo compound (II) is preferably carried out in such a way that either
• an aqueous alkali metal nitrite solution is introduced into the present aqueous suspension of the hydroxyaminoazobenzene of the formula (II) and of the phenol of the formula (III) in an aqueous mineral acid.
• the concentration of the mineral acid, such as hydrochloric acid, sulfuric acid or phosphoric acid, in the respective diazotization mixture should correspond to a normality of from about 10 -2 to about 5, preferably from about 10 -1 to about 2.
• alkali metal nitrite for example solution nitrite
• equivalent amount calculated on the diazotizable amino group; in order to ensure a complete diazotization, it is sufficient to apply an excess amount of nitrite in the range of from 1 to 5% of the equivalent amount.
• the temperature is in the range of from -20° to +20° C, however, preferably from 0 to 5° C.
• the amount of phenol present in the diazotization process may vary within wide limits.
• the diazotization is carried out in the presence of from about 5 to 150 molar %, however, preferably from about 10 to 105 molar % of the amount equivalent to the hydroxyaminoazobenzene.
• the coupling of the so-obtained diazonium salt of the aminoazo compound (II) with the phenol (III) already present in the diazotization mixture is achieved by adding an alkali metal hydroxide solution or an alkali metal carbonate or -acetate, such as sodium carbonate or sodium acetate, in a solid form or dissolved in water, optionally after having increased the phenol proportion to the amount which is equivalent to the diazonium salt.
• the coupling may also be effected in such a way that the suspension of the diazotized compound (II) in admixture with an equivalent amount of the phenol (III) is introduced into an aqueous sodium carbonate solution.
• the pH range which is most favorable for the coupling reaction is from about 3 to 11.
• the diazotization process of the invention for preparing the disazo dyestuffs (I) on the basis of p-phenylene-diamines (IV) is advantageously carried out as follows:
• the diamine (IV) is at first monodiazotized (first diazotization), and the 4-amino-benzene-diazonium salt obtained is then reacted with phenol (III) in a considerable excess amount, to yield hydroxyaminoazobenzene (II) (first coupling).
• the novel diazotization process now permits to further diazotize the intermediate product (II) formed in a direct manner (second diazotization), without previously isolating this compound in the form of the phenol-free product, as it has been the usual method so far.
• reaction product is coupled (second coupling) with the phenol left over the first coupling, which has optionally been filled up to the amount equivalent to that of the diazotized intermediate product (II), to give the dyestuff (I).
• the considerable excess amount of phenol used in the first coupling reaction has a favorable effect both on the reaction time and on the quality of the hydroxyaminoazobenzene being formed.
• 4-amino-benzene-diazonium salts belong to the slightly electrophilic and thus less active diazonium salts, as has already been known. This leads to the effect that their coupling with phenols which are present only in slight excess amount also develops only in a very low rate.
• the reaction of the 4-amino-benzene-diazonium salt with twice the equivalent amount of phenol to give 4-hydroxy-4'-aminoazobenzene at a pH value of from 9.0 to 9.5 and at a temperature of 25° C is completed within 30 minutes, whereas with an excess amount of only 5% it takes about 6 hours under the same reaction conditions.
• the excess amount of phenol in the first coupling reaction is as a rule in the range of from about 10 to 105% of the amount equivalent to that of the 4-amino-benzene-diazonium salt.
• the lower limit of about 10% of phenol excess is a pre-condition for obtaining an unobjectionable reaction product with a coupling that is effected as fast as possible.
• the upper limit of 105% of phenol excess is based on the fact that on the one hand a further increase of this excess amount does not generally have a favorable influence on the reaction rate and the quality of the reaction product and that on the other hand an excess amount of this level usually meets the requirement of coupling component in the second coupling.
• the reaction mixture is introduced for coupling into a solution of 25 parts by weight of sodium carbonate (Na 2 CO 3 . H 2 O) in 200 parts by volume of water, while stirring.
• sodium carbonate Na 2 CO 3 . H 2 O
• the reaction mixture is heated to 80° C, the dyestuff is dissolved in 40 parts by volume of a 33% by weight sodium hydroxide solution, then the mixture is stirred for about 15 minutes at the specified temperature, and the dyestuff is precipitated again by adding 50 parts by volume of a 31% by weight hydrochloric acid.
• the dyestuff is suction-filtered, washed until it is free from salt and dried.
• the solution obtained is then introduced, while stirring, into a mixture of 600 parts by volume of 31% by weight hydrochloric acid and about 2500 parts by weight of ice.
• the diazotization of the 4-hydroxy-4'-aminoazobenzene is completed when an excess of from 0.5 to 1 part by weight of sodium nitrite can still be dectected after 30 minutes.
• the reaction mixture has in this case a hydrochloric normality of from 0.3 to 0.5.
• the diazonium salt suspension obtained is introduced into a solution of 400 parts by weight of sodium carbonate (Na 2 CO 3 .sup.. H 2 O) in 400 parts by volume of water and 600 parts by weight of ice.
• the reaction mixture is continued to be stirred for 30 minutes, then it is heated to 80° C for after-treatment; the dyestuff is dissolved by adding 450 parts by volume of 33% by weight sodium hydroxide solution, is stirred for 15 minutes at the specified temperature and is reprecipitated by adding 550 parts by volume of 31% by weight hydrochloric acid. Thereafter the dyestuff is suction-filtered and washed with water until it is free from salt. After drying, 272 parts by weight of the valuable disazo dyestuff of the formula (VIII) are isolated.
• the diazonium salt is coupled so rapidly that the 4-hydroxy-4'-amino-azobenzene compound formed may be dissolved immediately after combining te reaction components with 100 parts by volume of a 2N-sodium hydroxide solution.
• a 1N-sodium nitrite solution After having added 95 parts by volume of a 1N-sodium nitrite solution, the solution is introduced, while stirring, into a mixture of 80 parts by volume of 31% by weight hydrochloric acid and 750 parts by weight of ice.
• the reaction mixture is continued to be stirred for 30 minutes with a small excess of nitrite which is subsequently reduced with a few drops of an amidosulfonic acid solution.
• Example 4 If in Example 4 the 15.3 parts by weight of 2-nitro-1,4-diaminobenzene are replaced by 17.6 parts by weight of 2-trifluoromethyl-1,4-diaminobenzene, the disazo dyestuff of the formula (X) ##STR11## is obtained which dyes polyester fabric in a yellow shade.
• the 4-hydroxy-4'-amino-azobenzene compound is dissolved by adding 180 parts by volume of 2N-sodium hydroxide solution, 19 parts by volume of 5N-sodium nitrite solution are added, and the solution is introduced, while stirring thoroughly, into a mixture of 80 parts by volume of 31% by weight hydrochloric acid and 750 parts by weight of ice.
• the mixture is continued to be stirred for 30 minutes with a small excess of nitrite, said nitrite excess is then removed and the diazonium salt suspension is introduced into 400 parts by volume of 2N-sodium carbonate solution.
• the mixture is continued to be stirred for 1 hour.
• the dyestuff is reprecipitated at 80° C and then isolated. 33 Parts by weight of the disazo dyestuff of the formula (XI) ##STR12## are obtained which dyes polyester fabric in a yellow shade.
• Example 6 If in Example 6 the 2,6-dichloro-1,4-diaminobenzene is replaced by the 2,5-dichloro-1,4-diaminobenzene and the process is otherwise carried out has been described in said Example, the disazo dyestuff of the formula (XII) ##STR13## is obtained which also dyes polyester fabric in a yellow shade.
• hydrazine is allowed to act -- in the presence of Raney nickel -- on 18.2 parts by weight of 2-nitro-5-amino-4-methoxy-toluene in 100 parts by volume of water, until no nitro compound can be detected any more.
• the 2-methoxy-5-methyl-1,4-diaminobenzene having been formed is dissolved by an addition of hydrochloric acid up to a pH value of from 2 to 2.5.
• the diamine is monodiazotized at a temperature of from 0° to 5° C in the pH range of from 1.5 to 3.5 with a further addition of hydrochloric acid.
• the process is carried out according to the specifications of Example 6 and a disazo dyestuff of the formula (XIII) ##STR14## is obtained which dyes polyester fabric in an orange shade.
• Example 2 If in Example 2 the 180 parts by weight of phenol are replaced by 234 parts by weight of 2,6-dimethyl-phenol and the process is otherwise carried out as has been described in said Example, the disazo dyestuff of the formula (XIV) ##STR15## is obtained which dyes polyester fabric in a reddish yellow shade.
• Example 2 If in Example 2 the 180 parts by weight of phenol are replaced by 207 parts by weight of 4-methyl-phenol and the process is otherwise carried out as has been described in said Example, the dispersion dyestuff of the formula (XV) ##STR16## is obtained which dyes polyester fabric in a reddish yellow shade.
• Example 2 If in Example 2 the 180 parts by weight of phenol are replaced by 207 parts by weight of 3-methyl-phenol and the process is otherwise carried out as has been described in said Example, the disazo dyestuff of the formula (XVI) ##STR17## is obtained which is excellently suitable, according to German Patent Specification No. 1 644 261, for the dyeing of polyester fiber material and yields strong orange color shades on the same.
• Example 2 If in Example 2 the 108 parts by weight of p-phenylene-diamine are replaced by 142.5 parts by weight of 2-chloro-1,4-diamino-benzene and the reaction is otherwise carried out as has been described in said Example, the dyestuff of the formula (XVII) ##STR18## is obtained which according to German Offenlegungsschrift No. 1 469 774, Example 7, dyes polyester and cellulose acetate fiber material in orange color shades having good fastness properties.

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Citations (6)

• 1976
  • 1976-04-21 DE DE2617302A patent/DE2617302C3/de not_active Expired
• 1977
  • 1977-04-18 CH CH476577A patent/CH624976A5/de not_active IP Right Cessation
  • 1977-04-19 US US05/788,763 patent/US4115380A/en not_active Expired - Lifetime
  • 1977-04-19 GB GB16164/77A patent/GB1578391A/en not_active Expired
  • 1977-04-19 IT IT22623/77A patent/IT1080354B/it active
  • 1977-04-20 BR BR7702495A patent/BR7702495A/pt unknown
  • 1977-04-20 JP JP4460577A patent/JPS52129731A/ja active Pending
  • 1977-04-21 BE BE176884A patent/BE853802A/fr not_active IP Right Cessation
  • 1977-04-21 FR FR7712004A patent/FR2348951A1/fr active Granted

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